Swallows and Amazons

During the school holidays, the Walker children (John, Susan, Titty and Roger; the Swallows) are staying at a farm near a lake in the Lake District. They sail a borrowed dinghy named Swallow, and camp on an island in the lake that they call Wild Cat Island. There, they meet two local girls, Nancy and Peggy Blackett, who sail a dinghy named Amazon and live in Beckfoot a house up the nearby Amazon River. The scene is set for rivalry as the Blacketts claim the island as their territory. The Swallows agree to join forces with the Amazons against a common enemy - the Blacketts' Uncle Jim (Ronald Fraser), whom they call "Captain Flint" after the character in Treasure Island, and his grumpy demeanor. To determine who should be the overall leader in their campaign, the Blacketts and the Walkers have a contest to see which can capture the others' boat. In the end, Titty seizes the Amazon when the Blacketts come to Wild Cat Island, leading to a mock battle between "Captain Flint" and the children, after which Uncle Jim is tried for his crimes and forced to walk the plank on his own houseboat.